Download Chapter 10 -- Navigation

Chapter 10
Navigation
Objectives
(1 of 3)
• Define the following terms or concepts:
– Determining distances
– Contour lines
– True north
– Grid north and magnetic north
Objectives
(2 of 3)
• Demonstrate the use of the UTM (Universal
Transverse Mercator) Grid System to
determine the coordinates for a given point.
• Describe the procedures used to obtain a
back azimuth.
• Describe how to take bearing in the field and
transfer it correctly to the map, and obtain a
bearing on the map and transfer it correctly to
the field.
Objectives
(3 of 3)
• Describe techniques used to navigate during
daylight hours while wearing a 24-hour pack.
• List three advantages and three limitations of
GPS (Global Positioning System) units as
employed during search operations.
Global Mapping
• Geographic mapping
• Geographic Coordinate System (latitude and
longitude)
• Universal Transverse Mercator (UTM)
• Universal Mapping System (UMS)
• Township and Range
• San Diego Mountain Rescue Team (SDMRT)
Geographic Mapping
(1 of 2)
• Uses specific known geographic
locations
• Good for use as reference points
• References can be measured in travel
distances.
Geographic Mapping
•
•
•
•
(2 of 2)
Requires little or no training
Easily learned
Best suited for novices
A good backup for more sophisticated
mapping systems
Geographic Coordinate System
Latitude and Longitude
(1 of 4)
• One method to identify points on a curved
surface of the Earth
• System of reference lines
– Parallels of latitude
– Meridians of longitude
Latitude and Longitude (2 of 4)
• On most modern maps, meridians and
parallels appear as curved lines.
• Important properties are shown with minimum
distortion
• Map projection
– System used to portray a part of the round
Earth on a flat surface
Latitude and Longitude
•
•
•
•
(3 of 4)
Grid system that covers entire globe
Longitude (meridians) run north-south.
Latitude (parallels) run east-west.
Practice is required to accurately describe a
point in the field.
Latitude and Longitude (4 of 4)
• Not as effective for ground personnel who
require accuracy
– Better for use with aircraft and boats
• Works well for all-around, general use when
exchanging information between ground and
air units
Longitude
• Any point is measured by an angle in degrees
up to 180 in either direction.
• Prime meridian
– Considered zero as the angular distance
east or west
• The International Date Line
– At 180-degree
– Connects with the prime meridian
Latitude
• Latitude starts at the equator,which is
considered zero.
• Lines of latitude are parallel to the equator.
• Latitude lines are referred to as parallels.
• Angular distance is measured in degrees with
90 being the maximum at each pole.
Universal Transverse
Mercator (1 of 6)
• Special grid for military use
• The world is divided into 60 north-south
zones.
• Each zone covers a strip 6° wide in
longitude.
Universal Transverse
Mercator (2 of 6)
• Zones are numbered consecutively with Zone
1 between 180° and 174° west longitude and
progressing eastward to Zone 60, between
174° and 180° east longitude.
Universal Transverse
Mercator (3 of 6)
• Coordinates are measured north and east in
meters.
• One meter equals 39.37 inches, or slightly
more than 1 yard.
• Northing values are measured continuously
from zero at the equator in a northerly
direction.
Universal Transverse
Mercator (4 of 6)
• The Equator was assigned an arbitrary false
northing value of 10,000,000 meters.
• Central meridian through the middle of each
6° zone is assigned an easting value of
500,000 meters.
• Grid values to the west of this central
meridian are less than 500,000; to the east,
more than 500,000.
Universal Transverse
Mercator (5 of 6)
• UTM grids lines
– Shown on all USGS quadrangle maps
– Indicated at intervals of 1,000-meters
– Indicated by either blue ticks in the margins
of the map or with full grid lines
• The 1,000-meter value of the ticks is shown
for every tick or grid line.
Universal Transverse
Mercator (6 of 6)
• On a 7.5-minute map, each tick is
represented by four numbers.
– Superscript numerals: 1,000,000- and
100,000-meter grids
– Last two numerals: 10,000- and 1000meter grids
• 4998 = 4,998,000 meters north of the Equator
Universal Mapping
System (1 of 5)
• Devised in Washington State in the mid
1960s
• Widely used prior to handheld GPS devices
• Designed to help air and ground operations in
communicating locations
• UTM and geographic coordinate systems
have almost completely supplanted UMS.
Universal Mapping
System (2 of 5)
• Uses letters and numbers to describe points
• Tied into Sectional Aeronautical Charts
(1:500,000)
• Used by Civil Air Patrol and USAF
• Also keyed into 15-minute topo maps that
have been abandoned by the USGS
Universal Mapping
System (3 of 5)
• Example: SFO 123 B 4567
• “SFO” designates the three-letter name of the
Sectional Aeronautical Map.
• “123” represents a 15-minute quad.
• “B” represents the upper right quadrant (A is
upper left, C is lower left, and D is lower
right).
Universal Mapping
System (4 of 5)
• “4567” represents measurements made from
the corner of the 7.5-minute quad,
horizontally first, then vertical.
• “45” represents 4.5 miles horizontally from
the upper right corner.
• “67” represents 6.7 miles vertically from that
point.
• The entire designation describes an areas
1/10th of a square mile.
Universal Mapping
System (5 of 5)
• Difficult to teach and apply in the field,
especially if not used often
• Possibly a consequence of attempting to
adapt an air search system to ground SAR
operations
• Some swear by its effectiveness.
Township and Range
(1 of 3)
• In 1785, the U.S. Public Land Survey was
started with territories northwest of the Ohio
River as a test area.
• The land was divided into townships 6 miles
square with boundaries running north, south,
east, and west.
• Townships were to be subdivided into 36
numbered sections of 1 sq. mile (640 acres)
each.
Township and Range
(2 of 3)
• Surveys were not completed.
• System is not applicable to many parts of the
U.S.
• Should not be used for navigation
– Lines do not always run true north/south or
true east/west as originally intended.
Township and Range
(3 of 3)
San Diego Mountain
Rescue Team (1 of 3)
• Simple, fast, and easy to learn
• The SDMRT system will work on any map.
• Useless without a map so it cannot be strictly
considered a method of absolute navigation.
San Diego Mountain
Rescue Team (2 of 3)
• First: Identify the map to be used by scale
and quadrant name.
• Second: Use a measuring device to measure
the point from the nearest border.
• Coordinates are read by indicating distance in
inches from the left map margin and from the
bottom margin.
• “Read Right Up”
San Diego Mountain
Rescue Team (3 of 3)
• Take measurements from map margin and
not the edge of the map.
• Map edge is not used because large
variances exist from one map to another.
• Can be used on any map as long as it has a
border and the user has some type of
measuring device.
Topographical Maps
(1 of 10)
• Portray the shape and elevation of the terrain
• Show graphic representation of selected
manmade and natural features to scale
Topographical Maps (2 of 10)
• USGS publishes topo maps in a variety of
scales.
– Most popular for land SAR is the 7.5minute map.
• 7.5-minute maps have quadrangle
dimensions of 7.5 minutes.
• Available as digital files on CD-ROM
computer disk
Topographical Maps
(3 of 10)
• USGS maps are supposed to be updated
every 5 to10 years, but often it is longer.
• They accurately depict terrain and relief
(elevation and slope).
• Manmade features may differ.
Topographical Maps (4 of 10)
• Top of the map is always true north.
• Vertical lines of longitude point north and
south.
• Horizontal lines of latitude point east and
west.
• Space outside the margin line identifies and
explains the map.
Topographical Maps (5 of 10)
• Identified in the upper right margin by
quadrangle name, state or states in
which it is located, series, and type
• Usually named after a prominent,
immoveable place or landmark within
the mapped area
Topographical Maps (6 of 10)
• “Series” refers to the area mapped in terms of
minutes or degrees.
• “Type” is either topographic or plenimetric.
• Title block in lower right margin shows
quandrangle name, state name, and
geographic index number.
Topographical Maps (7 of 10)
• Geographic coordinates are shown:
– At all four map margin corners
– Along the margin lines at 2.5-minute
intervals for 7.5-minute maps
• Credit legend is located in the lower left
margin.
– Due to the infinite data, credit legends
cannot be rigid.
Topographical Maps (8 of 10)
• Magnetic declination for the year of filed
survey or revision
– Determined to the nearest 0.5 degree from
the latest isogonic chart
– Shown by a diagram centered between the
credit legend and bar scale
• The declination diagram indicates the angular
relationship between true north, grid north,
and magnetic north.
Topographical Maps (9 of 10)
Topographical Maps
(10 of 10)
• Center of the lower margin contains:
– Publication scales expressed as a ratio
– Bar scales in metric and imperial units
– Contour-interval statement
– Vertical datum
– Depth-curve sounding statement
– Shoreline and tide-range statements
– Map accuracy statements
Road Symbols
(1 of 2)
• Legend is placed in the lower right margin.
• Tailored for each map to include only
classes of roads and route markers that are
shown in the body of the map
• Trails are not included in the legend unless
there are no roads on the map.
Road Symbols
(2 of 2)
Colors on the Map
•
•
•
•
•
•
Brown: Contour lines
Green: Vegetation
Blue: Water
Black: Manmade objects
Red: Roads and built-up areas
Purple: New changes or updates on the map
Contour Lines
• Represent relative elevation
• Each contour line connects all points at the
same elevation above sea level.
• Three types:
– Index
– Intermediate
– Supplementary
Index Contour Lines
• Every fifth line is darker.
• Have numbers superimposed on them
indicating the elevation along that
particular line
Intermediate Contour Lines
• Lighter brown lines
• Fall between index lines
• Are not numbered
Supplementary Contour Lines
• Dashed lines that may be used when:
– The terrain is very flat
– There are large distances between contour
lines
• Shows a difference in elevation that is half of
the elevation of the contour lines between
which it falls
Terrain Features (1 of 5)
• Terrain features evolve from a complex
landmass known as a “ridgeline. ”
• A ridgeline:
– Is a line of high ground
– Usually has variations in elevation along its
top
• A “ridge” is simply one of the terrain features
that may arise from a ridgeline.
Terrain Features
(2 of 5)
Terrain Features
(3 of 5)
• A total of ten natural or manmade features
may arise from a ridgeline.
• Each feature has unique and notable
characteristics.
• These features fall into two categories:
– Major terrain features
– Minor terrain features
Terrain Features (4 of 5)
Terrain Features (5 of 5)
• Major features:
– Hills
– Saddles
– Valleys
– Ridges
– Depressions
• Minor features:
– Draws
– Spurs
– Cliffs
– Cuts/Fills
Compass Types
• Two styles of compasses:
– Orienteering
– Lensatic
• The orienteering style is preferred for
SAR.
• All compasses have similar basic
features.
Compass Characteristics
•
•
•
•
•
•
Base plate or base
Bezel, dial, ring, or compass housing
Bearing/orienting lines
Magnetic needle
Direction of travel arrow
Index line or lubber line
• Sighting mirror
Orienteering Compass
Navigating with a
Compass (1 of 2)
• Good compass posture:
– Stand still with arms comfortably at sides.
– Elbows bent so that both hands can hold
the compass directly in front of body
– Hold compass at either chest-level or beltlevel.
Navigating with a
Compass (2 of 2)
• Ensure that direction of travel arrow is
pointing in the same direction as your toes.
• Toes must be pointing in the same direction
as the direction of travel arrow
• When you move the compass to a specific
heading, move your entire body as a solid
extension.
• Hold the compass level so that the needle
may move freely to settle on a direction.
Following a Heading
• Point your toes in direction you wish to
travel and sight a prominent object in the
distance.
• Close your eyes for several seconds,
open them, and confirm you can find the
object.
• Reconfirm your heading to object, lower
the compass, and start walking.
Using a Map and
Compass Together (1 of 3)
• The compass is used primarily as a protractor
and ruler.
• 360-degree dial, in association with the
orienting lines in the base of the bezel, serve
as the protractor.
• Straight sides of the base serve as a straight
edge.
• The magnetic needle can be completely
ignored.
Using a Map and
Compass Together (2 of 3)
• To determine the heading from one point to
another on the map:
– Place the compass on the map so that one
edge of the base plate touches both the
starting point and the destination.
– Make sure that the direction of travel arrow
is pointing in the correct direction of travel.
Using a Map and
Compass Together (3 of 3)
• Turn the dial ring until the orienting arrow,
with the arrow pointing north, is parallel to
the nearest north-south meridian.
• The heading from the starting point to the
destination is now indicated on the dial
ring.
• Scales on bottom margin can be used to
measure distance on the map.
Magnetic Declination
• The angle between the direction the magnetic
needle points (magnetic north) and true north
• The magnetic needle on a compass only points
to true north when the compass is along the
“Agonic” line.
• East of this line, a compass needle will point
west of true north (west or negative declination).
• West of this line, a compass needle will point
east of true north (east or positive declination).
Magnetic Declination
• If you know the magnetic declination of the
area in which you will be navigating, you have
four options:
– Ignore it.
– Adjust for it on the compass.
– Adjust for it by drawing magnetic meridians
on the map.
– Adjust for it mathematically.
Ignore it
• When using a compass without a map
• When operating on the Agonic line
Adjust the Compass
• Some compasses can be adjusted for
declination.
• Offsets the orienting arrow and index line in
the base of the bezel to compensate for
declination when the compass is used as a
protractor with a map
• Once adjusted, the orienting arrow in the
bezel is no longer parallel to the orienting
lines.
Draw Magnetic Meridians
• Prepare the map by adding magnetic north
lines to it .
• Adding these lines requires a protractor, long
straight edge, and the angle of declination.
• Not recommended for SAR due to difficulty in
accomplishing this manually.
• Added lines may make map more difficult to
read.
Mathematical Correction
• Must know if the declination is east or west.
• Look at the declination diagram at the bottom
margin of the map.
– If “MN” is to left of the star, declination is
west.
– If “MN” is to right of the star, declination is
east.
• Determine if you are going from map to
compass or compass to map.
Tally
(1 of 2)
• Distance can be measured by knowing
the length of one’s stride and multiplying
it by the number of strides walked
• A stride, is equivalent to 2 steps, or the
distance between where one foot strikes
the ground and where the same foot
strikes the ground again
Tally
(2 of 2)
• Strides will vary depending on leg length,
terrain, weather, darkness, fitness, and many
others
• Valuable skill in several situations in SAR –
estimating distance when a mapped object or
area is a known distance from a starting
point. Also, being able to estimate how far a
clue was found from the start of a search
might be valuable during debriefing
Global Positioning System
(1 of 2)
• A space-based radio navigation system
consisting of satellites and a network of
ground stations
– Use for monitoring and control
– A minimum of 24 GPS satellites orbit the
Earth.
• The principal behind the GPS is the
measurement of distance between the
receiver and the satellites.
Global Positioning System
(2 of 2)
• Limitations
– Requires line-of-sight to the satellites and
will not work in all terrains.
– Should not be used as sole navigation
device
– Less than perfect accuracy
– Human error
– Position display can easily be misread.
– Typical battery life is 4-6 hours.